Tonight’s Full Moon could be hard to miss. Remarkably, its exact full phase (May 6 03:36 UT) will occur less than two minutes after it reaches perigee, the closest point to Earth in the Moon’s orbit, making it the largest Full Moon of 2012. The Full Perigee Moon will appear to be some 14 percent larger and 30 percent brighter than a Full Moon near apogee, the most distant point in the elliptical lunar orbit. In comparison, though, it will appear less than 1 percent larger and almost as bright as April’s Full Moon. Of course, if you miss May’s Full Perigee Moon, make a note on your calendar. Your next chance to see a Full Moon close to perigee, will be next year on June 23.

Effect on tides

The combined effect of the Sun and Moon on the Earth’s oceans, the tide, is greatest when the Moon is either new or full. At lunar perigee the tidal force is even stronger, resulting in larger high and low tides on average, but even at its most powerful this force is still weak.

This is a list of the 20 brightest stars as seen from the Earth (not including the Sun). The stars are numbered from 1 to 20 in sequence.

Common Name

This is the name by which the star is commonly known. The names are Greek, Latin or Arabic. This web site is based in London: stars not visible from London are in red.

Some examples of the names: Deneb is Latin for tail(because it marks the tail of The Swan – Cygnus); Antares is Greek for rival of Mars(because of its red colour); Aldebaran is Arabic for eye of the bull (because it marks the eye of The Bull – Taurus).

Constellation

A constellation is a star group (as seen from Earth) that the star is a part of. Constellations are human inventions. The stars in them appear in the same part of the sky but are, in fact, at different distances from us and not related to each other. Different cultures use different constellations. For more, read Astronomy and Astrology.

In the West, there are 88 recognised constellations; 48 of these date from Roman times and are known as the Classical Constellations. These include the 12 Zodiac constellations through which the Sun, Moon and planets always pass through. Constellations are always known by their Latin names.

Constellations are used by astronomers for convenience. We say that Sirius is in Canis Majorrather than give its celestial coordinates.

Apparent Magnitude

Apparent Magnitude tells how bright the star is as seen from the Earth. The magnitude scale was devised by the Ancient Greeks. The brightest stars were called First Magnitude, the next brightest were called Second Magnitude, etc.

In modern times, the scale has been defined mathematically. A star of magnitude 1 is about 2.5 times brighter than a star of magnitude 2 which in turn is 2.5 times brighter than a star of magnitude 3. The brighter a star, the smaller its magnitude. Many stars are brighter than first magnitude. Some stars are so bright they have negative magnitudes. On this scale, Jupiter has a magnitude (at its brightest) of -2.6, Venus is at -4.4 and the Sun -27. The faintest stars visible to the naked eye are sixth magnitude. Pluto has a magnitude of +14, far too faint to be visible without a powerful telescope.

In the table it can be seen that Betelgeux varies its magnitude – some stars are variable in brightness.

The brightness of a star as seen from Earth depends on its intrinsic luminosity and its distance from Earth. A dim star may appear bright because it is close while a luminous star may appear faint because it is far away. This is why we sayApparent Magnitude.

Spectral Type

When starlight is passed through a prism, it splits into its constituent colours, like a rainbow. This is called the star’s Spectrum. Stellar spectra are crossed by dark lines. These lines give astronomers a lot of information about the star: temperature, luminosity, radius, magnetic properties, movement. Read The Electromagnetic Spectrum for more on spectra.

The Morgan-Keenan spectral classification (Photo credit: Wikipedia)

Stellar spectra are classified into types. These types are given letters. The spectral type series is a temperature series. Moving from the hottest stars to the coolest, the series of letters runs O, B, A, F, G, K, M.

Each spectral type is subdivided into ten numbers. For example, A0, A1, A2, up to A9. A0 is hotter than A1. The table below gives more information.

Spectral
Type

Colour

Surface
Temperature
(°C)

O

Blue

>30,000

B

Blue-White

20,000

A

White

10,000

F

Yellow-White

7,000

G

Yellow

6,000

K

Orange

4,500

M

Red

3,000

Our Sun is a star of Spectral Type G2 with a surface temperature of around 6,000°C.

Luminosity

This tells us how much more energy and light the star gives off compared with the Sun. This is how bright the star really is once distance has been taken into account. There is a huge variety in the luminosity of the stars. At one extreme, the star Alpha Centauri is 1.7 times more luminous than the Sun. At the other extreme, Canopus is 15,000 times more luminous than our Sun.

Luminosity can be measured indirectly by combining the apparent brightness of a star with its distance. It can also sometimes be measured directly from the spectrum.

Distance

The distance of a star is given in Light Years. This is the distance covered by a light beam in one year. Light travels at 300,000 km per second (186,000 miles per second). In one year a beam of light will travel 9.4 million million km (5.9 million million miles). This enormous distance is a Light Year.

Many stellar distances can be measured directly by trigonometry. As the Earth moves around the Sun, the star appears to shift its position against more distant stars. This effect is called parallax. It is a tiny effect but can be measured. The amount of the parallax depends on the diameter of the Earth’s orbit around the Sun (just under 300 million km or 186 million miles) and the distance to the star. A star with a paralax of 1 second of arc (written 1″) is said to be at a distace of 1 Parsec. 1 Parsec is equal to 3.26 Light Years.

Other stars can have their luminosity measured by their spectra or by other properties. When this is compared to their apparent brightness, a distance can be calculated.

This the velocity of the star relative to the Sun. Negative velocities denote a star moving towards the Solar System. Positive velocities are for stars moving away from us.

Radial velocity is easily measured by looking at the star’s spectrum. The lines on the spectrum are shifted to the blue end if the star is moving towards us (the so-called blue shift) and to the red end if the star is moving away from us (red shift). The amount of this shift depends on the relative velocity between us and the star.

Eyes on the Sky: Apr 16 thru Apr 22

Catch a couple crescents and eyeing Orion

Late waning and early waxing (i.e., very thin) crescent Moons are beautiful sights, but can be tough to spot and see. Eyes on the Sky will show you where to look in the early morning this week to see the slender waning crescent Moon in the eastern sky, then where to look again as the Moon reappears in the evening western sky.

Orion is fading into the southwestern evening sky, but still remains high enough while it is dark to spot some interesting double stars spotted with binoculars or with a small telescope. Don’t miss the 3-D “zoom in” perspective of Orion’s belt stars, which all appear to be in a line and of equal distance – check out the surprising result of zooming in! And lastly, with the “Mayan calendar” hype occurring, learn a bit about what the Maya saw in this part of the sky too.

Eyes on the Sky: Apr 2 thru Apr 8

The planet-spectacular, “Planet-acular”!

There are four (count ’em, four) naked eye planets visible in the evening sky this week, and three of them are near some interesting types of stars. See Jupiter and Venus in the early evening and Mars and Saturn nearly all night long. A couple of these planets are joined by the Moon, the planets themselves contrast nicely with some spectral class “B” stars, and now is the time to get a jump on the necessary equipment for solar viewing, with the Transit of Venus approaching in early June. There’s good reason to starting thinking about appropriate solar equipment now. AND… the Moon offers up some “shadowy” treats of it’s own – and many of these sights can be seen in very small telescopes or (sometimes better) with binoculars. So get outside this coming week and see what’s up!

Like this:

The Constellations Table :A complete table with information about all the 88 Constellations as defined by the I.A.U. ( International Astronomical Union ). Abbreviations, Genitive and Latin Names, English Names and more.FIELD LIST

Forgetting my new pair of binocs was not something willed upon but New Year 2012 was approaching and as the hump-jump was everywhere, the sky was absolutely something to be forgotten about.

Do, you think the sky can be just something taken for granted and not taken care about? Obviously, for the half of my life I had never taken any interest with the sky, nor does the mass of dumbed down populace.

So why this sudden rush to understand the sky now??

The sky has been always there, neither it is so “enchanting” nor “magnetic” but our eyes are so riveted to our laptop screens or our TV sets that we have almost no time to care for what’s happening above us. Or, to just even ponder about a sky so beautiful with all its mysteries there waiting to be explored upon.

The creation of the heavens and the earth is indeed greater than the creation of mankind; yet, most of mankind knows not.

(Quran 40:57)

At 12:00 a.m midnight, around the world as it is, the festivities started with the fire works show.

In Mauritius, at the peak of the Signal Mountain this fireworks time-lapse was taken.

Unbelievingly, by one in the morning of January 2012, everything quietened up. The night was still. No stirring up of even the leaves on trees around.

I am still thinking why did I go out that night rather than sleep?

So, my first observation did happen on 01/01/2012. How do I remember this? I think reading a review somewhere I came upon the advice that if you are entering this amateur astronomy hobby, ever if you are observing even for a few minutes , just record the observations. It would help you a lot.

How?

Personally, while reviewing at my log notes in my personal diary, I looked foolish of what I had logged as my first observations, but it was so interesting that an amateur as me brought in my own astronomy definitions on my first time to the already defined observable universe.

Nevertheless, the first observation remains the best and the most memorable.

And surprisingly the whole world is also. Take any beginner’s guide to the sky, they would talk only Orion,Orion, Orion. I didn’t know about Orion or its belt, but perhaps this was a sign from The Creator that this is where you should start your journey to the universe. There is so much I have learned about these three that I am baffled and there is still more to come.

The actual observation

Standing towards the west, I saw this magnificently in front of me.

I continuously looked at this portion of the sky for 2 hrs straight

What I actually wrote as observational notes?

Night gazing: The axe

Naked eye: Concentrated dots

Binocs: Small dots.

01:00 – 03:00 am

I also drew the dots in a diary.

What makes me foolish looking now is that I called the Orion belt as the axe’s blade and the Orion Nebulae as the axe’s handle.

Hey, if the Greeks can make out Gods out of stars why can’t I make my own Axe?

The Orion Hunter

So, I have already fallen in love with the sky, what are you waiting to raise your eyes to the beautiful night sky?

Reading an article on beginners in amateur astronomy, I came to understand that my search for telescopes is not at the right time. Telescope will not allow you or put you on the night viewing passion, but rather not knowing its efficient use may also lead its place to the closet.

Usually it is advised for any requiring hobby to start on by buying this or buying that. I was rather astonished to the fact that most experienced amateur astronomers usual first time advice is to get familiar with the night sky, with the constellations and with the stars before buying anything. (As if they know, that once you get in this field then your aperture fever or drooling on the latest equipment never dies).

Therefore, I took the advice to buy a binocular first rather than buying the telescope. And in fact the next day, I went to buy my first binoculars. A 10 x 50. Explanation to what is this 10 x 50 is given in the following youtubes. I like this guy’s simple explanations.

But my astonishment found no bounds when you come to know that binoculars are not only this size but can they be larger or bigger.

As to be said, the nerd notion was a bit less understood, so this post is an upgrade of nerdiness to be found in the amateur astronomy world. Browsing through the internet you find a lot but, which marks your interest may be only a selected few.

I regret the fact that there are others who call these people nerds or fools but I would rather call them enthusiasts.

You don’t even understand or need to understand the love they have for the night.